The derived metric as described in chapter~\ref{sec:metrics} has been tested to gain
insight on its applicability and granularity.

\subsection{Scenario: Switch port}
Enabling such test a number of assumptions were made:
\begin{itemize}
 \item The device is a 100 Mb/s 24 port Switch ($Speed_{max}=100*10^6$ b/s, $N_{ports}=24$)
 \item The power consumption is constant $P_{total} = 123 W$
 \item The utilization increases stepwise by 1\%
 \item The temperature is at room temperature. $T = 300 K$
\end{itemize}

Combining these assumptions yields data as presented in table~\ref{tbl:data}. The
leftmost column contains the calculated value for the \emph{absolute current energy
efficiency per port} $dB\varepsilon_{cpp}$.

\begin{table}[!h]
 \begin{center}
 \begin{tabular}{|l|l|l|l|l|}
 \hline
timestamp & realpower & utilization & bps & abseff \\\hline
1357588800 & 123 & 0.01 & 1000000 & 152.52 \\\hline
1357596000 & 123 & 0.02 & 2000000 & 149.51 \\\hline
1357603200 & 123 & 0.03 & 3000000 & 147.74 \\\hline
1357610400 & 123 & 0.04 & 4000000 & 146.49 \\\hline
1357617600 & 123 & 0.05 & 5000000 & 145.53 \\\hline
1357624800 & 123 & 0.06 & 6000000 & 144.73 \\\hline
1357632000 & 123 & 0.07 & 7000000 & 144.06 \\\hline
1357639200 & 123 & 0.08 & 8000000 & 143.48 \\\hline
1357646400 & 123 & 0.09 & 9000000 & 142.97 \\\hline
\multicolumn{5}{|c|}{...} \\\hline
 \end{tabular}
 \caption{Constant power consumption, increasing utilization in 1\% steps.}
\label{tbl:data}
\end{center}
\end{table}
\vskip2em

Figure~\ref{fig:graph_dbecpp} displays the data from table~\ref{tbl:data} in a graph
that shows the curve of \emph{absolute current energy
efficiency per port} $dB\varepsilon_{cpp}$ against the \emph{port utilization}.

\begin{figure}[!h]
 \begin{center}
  \includegraphics[width=\textwidth]{Figures/dbecpp.png}
 \end{center}
 \caption{Absolute current energy efficiency per port against port utilization.}
 \label{fig:graph_dbecpp}
\end{figure}

The graph in figure~\ref{fig:graph_dbecpp} shows how the absolute energy efficiency
rises, first steeply until about 20 - 30\%, than more gradual towards 100\%. On a
side note: The absolute energy efficiency is measured Decibel (dB), therefore a
decreasing value actually means a efficiency gain.\\
The steep raise in the first part of the graph can be explained by the fact that the
power consumption of the device stays constant, while the utilization (and thereby the
bit rate) raises. \\
In other cases regarding switches, when 802.3az (\emph{Energy-Efficient Ethernet}) is not in place the
proportions stay the same, because the fluctuation in the power consumption is
negligible. \\
Conclusion: Energy efficiency wise a port should be utilized above 40\%, if the power
consumption is constant.

\begin{figure}[!h]
 \begin{center}
  \includegraphics[width=\textwidth]{Figures/dbecpp_mb_gb.png}
 \end{center}
 \caption{Comparison of absolute current energy efficiency of 100 Mb/s and 1 Gb/s
 port.}
 \label{fig:graph_dbecpp_mb_gb}
\end{figure}
\vskip2em

Figure~\ref{fig:graph_dbecpp_mb_gb} elucidates the difference in efficiency of a 100
Mb/s port to a 1 Gb/s port, where all other all other variables are shared. It
substantiates and extends aforementioned conclusion, as the relationship between
utilization and efficiency stays the same on one hand and on the other hand the
general efficiency of the 1 Gb/s is distinguishable higher.
